Why are particles not rendered?
Go to  Render, select Object and choose your particle object, also Show Emitter.
Your emitter object is probably in another hidden layer and there for it will not show you your particle system.

Try resizing your particles on Render &gt; Size tab.
The shader assigned to the emitter is the ones the particles will inherit.

Unless you´re working with another object as particle, in which case it will select that object´s material as the particle material.